The best free alternative to Lucidchart is diagrams.net, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Lucidchart and loads of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Lucidchart are Dia (Free, Open Source), yEd Graph Editor (Free), LibreOffice - Draw (Free, Open Source) and Freeplane (Free, Open Source).
Mindix offers a very simple, clean and organized environment to capture ideas and take notes while conducting brainstorming sessions. Mindix allows you to create text and image entries and make connections between them to express ideas and concepts in your mind maps.
Creates diagrams from textual descriptions! It provides a unified API with support for BlockDiag, BPMN, Bytefield, C4 (with PlantUML), Ditaa, Erd, GraphViz, Mermaid, Nomnoml, PlantUML, SvgBob, UMLet, Vega, Vega-Lite, WaveDrom.
An online diagramming tool with built-in productivity features to create diagrams faster. Draw flowcharts, mind maps, org charts, network diagrams, Venn diagrams and 50+ other diagrams types. Readymade templates to get started fast.
The AXON Idea Processor provides an environment that supports the thinking processes. It helps you to create, communicate, explore, plan, compose, design, learn... and: Work with ideas & concepts rather than words. See the big picture and not get lost in details.
Breakdown notes: Make mindmaps and notes online for free. Breakdown Notes is a web-app to make notes, diagrams or mindmaps in your browser. It currenty works on desktop or laptop using recent version of Chrome or Firefox. It's free to use and requires no registration.